The present invention relates to skateboards, and, more particularly, to an improved skateboard having a plurality of trucks, each of which support two narrow wheels, spaced apart and rotatably mounted thereto. Each truck is rotatably mounted to an axle of the skateboard such that each truck is free to rotate independent of any other truck that is employed with the skateboard.
There are, of course, considerable number of skateboards currently in use and which, in general, comprise a footboard on which the user rides and has a pair of axles, a forward and a rearward axle depending upon the direction of travel, that are affixed to the underside of the footboard. The typical construction includes a rather wide, cylindrical wheel that is rotatably affixed to the outer ends of each of the axles. The typical axles are fixed in position to the footboard on which the rider is positioned and have opposite ends extending laterally outwardly with respect to the longitudinal axis of the skateboard. The wide wheels, in turn are also fixed with respect to the footboard and, as such, the wheels do not individually give or move as the skateboard encounters an obstruction such as a bump or crevice. Thus, a bump or obstruction can cause a problem in the performance of the skateboard and may, at times, stop the travel of that skateboard to the distress of the user.
There have been examples of skateboards having differing systems to alleviate the problems of encountering bumps or obstructions in the use of the device, and one such example is shown and described in U.S. Pat. No. 4,062,557 of Roden where there are front and rear trucks, each having four wide wheels and where the two trucks are allowed to pivot to a limited degree due to the means with which each of the trucks is affixed to the footboard. As can be seen in the Roden reference, both trucks themselves itself pivot each time any one of the wheels encounters an obstruction to enable the wheel hitting the obstruction to be raised to travel over the obstruction. However, at the same time, the other corresponding lateral wheel affixed to that same truck also moves upwardly along with the wheel hitting the obstruction. Thus, the other wheel that has not hit anything is unduly raised off of the surface on which the skateboard is moving and the skateboard is therefore unnecessarily compromised in its stability with respect to the ground. It would obviously be better if only the wheel that encounters the small bump be raised to travel over that bump and not affect the operation of other wheels and their contact with the ground, i.e. that the laterally spaced wheels operate independently with respect to each other. In addition, with the use of the wide wheels of Roden, the chance of encountering such small bumps increases and the wide wheels, having high compression shear, tend to try to pass over the bumps as opposed to pushing small obstructions, such as pebbles, aside and out of the way of the wheel.
Another example of a purported solution to the difficulties of encountering small bumps or obstructions in the operation of skateboards is shown and described in U.S. Pat. No. 4,337,961 of Covert et al, where the skateboard utilizes four trucks, each independently pivotally mounted for support of the footboard, however, in the Covert et al skateboard, there is used an endless belt that encircles each longitudinally spaced pair of wheels of each truck. The endless belt is mounted over wide wheels and contact with the ground is by means of the endless belt.
While, therefore, the individual, lateral sets of wheels are thus individually pivotable from their opposite spaced counterparts on any truck, the use of an endless belt itself creates a further problem. Skateboards are used in a rather rigorous environment and encounter a wide variety of maneuvers, among the most basic of which, are turns, some of which are quite sharp and deliberately aggravated. As such, when the skateboard is turned in direction by the user, the skateboard, bearing the weight of the user is forced outwardly by considerable centrifugal force and creates high lateral stresses on the wheels.
The use of an endless belt, therefore, would tend to be stressed laterally and would be forced off of the wheels in such a turn. In such case, obviously, the endless belt is highly susceptible to coming off the wheel and which is certainly an undesirable characteristic of such a skateboard. As a solution, it would be necessary to apply considerable tension to tighten the belt around the wheels to try to hold the belt on to the wheel during turns, however, that only creates the further problem that any debris that would be swept up by the endless belt would become lodged between the interior surface of the belt and the wheels and would cause considerable problems, either by stopping the belt and wheel movement or causing damage to the endless belt. Again, also, as in the Covert et al construction, the use of a wide belt raises the likelihood that the belt will try to travel over obstructions rather that to push them aside.